*Just a tip: before you read about cache, read about the CPU as well as about RAM, because essentially, cache is a faster form of RAM (memory)!
There are 2 main levels of cache: Level 1 cache (which is built directly into the CPU) and Level 2 cache (which is usually on the motherboard). You can think of cache as a place where your computer keeps frequently used data.
The overall idea is, if your CPU (processor) is looking for information to run its programs, it will first search the fastest cache, the Level 1 cache. If the information is found there, then the program is all set to run. If not, then the processor jumps to the slightly slower cache, the Level 2 cache. If it doesn't find the information there, the processor must go to the still slower "system RAM" (memory).
What I just described is called "system cache." There is also "web cache" and this has to do with your Internet browser (Internet Explorer, Firefox, etc). Basically, every time you visit a web site, your browser stores the information from that web site on your hard drive. That way, if you go back to visit that same web page, your browser can quickly pull up the saved web site and not have to re-download the web site from the Internet.
Why wouldn't we all just buy computers that only use Level 1 cache? The short answer is, that kind of ultra-fast memory is still very expensive. Also, when most programs run, they only use a small portion of data over and over, so you wouldn't necessarily need a Level 1 cache to make them work efficiently.
Cache
*Just a tip: before you read about cache, read about the CPU as well as about RAM, because essentially, cache is a faster form of RAM (memory)!There are 2 main levels of cache: Level 1 cache (which is built directly into the CPU) and Level 2 cache (which is usually on the motherboard). You can think of cache as a place where your computer keeps frequently used data.
Click here for a simple diagram of cache.
The overall idea is, if your CPU (processor) is looking for information to run its programs, it will first search the fastest cache, the Level 1 cache. If the information is found there, then the program is all set to run. If not, then the processor jumps to the slightly slower cache, the Level 2 cache. If it doesn't find the information there, the processor must go to the still slower "system RAM" (memory).
What I just described is called "system cache." There is also "web cache" and this has to do with your Internet browser (Internet Explorer, Firefox, etc). Basically, every time you visit a web site, your browser stores the information from that web site on your hard drive. That way, if you go back to visit that same web page, your browser can quickly pull up the saved web site and not have to re-download the web site from the Internet.
Why wouldn't we all just buy computers that only use Level 1 cache? The short answer is, that kind of ultra-fast memory is still very expensive. Also, when most programs run, they only use a small portion of data over and over, so you wouldn't necessarily need a Level 1 cache to make them work efficiently.
For sources and more information see:
http://www.pcguide.com/ref/mbsys/cache
http://www.wisegeek.com/what-is-cache-memory.htm
http://www.techterms.com/definition/cache
*Still a little confused? The website How Stuff Works has a great metaphor for cache which involves a librarian looking for books!
Defined By: Alissa Rosellini
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